| You can read this book from cover to cover if you like, but each hack stands on its own, so feel free to browse and jump to the different sections that interest you most. If there's a prerequisite that you need to know about, a cross-reference will guide you to the right hack. The book is divided into seven chapters, organized by subject:
Chapter 1, Broadband VoIP Services -
In this chapter, you'll be introduced to some Internet-based VoIP phone service providers who can help you replace your traditional phone line with a cost-saving, feature-rich VoIP line.
Chapter 2, Desktop Telephony -
Since VoIP is rooted in software, it has some wonderful uses on your desktop PC or Mac. In this chapter, you'll learn how to customize and maximize productivity-enhancing telephony applications.
Chapter 3, Skype and Skyping -
Skype, the ubiquitous desktop voice-calling application, is one of the most hackable desktop telephony tools, and therefore is worthy of an entire chapter of hacks.
Chapter 4, Asterisk -
Just as VoIP enables desktop telephony, it also enables enterprise telephony. In this chapter, you'll learn how to install, configure, and hack Asterisk, an open source PBX.
Chapter 5, Telephony Hardware Hacks -
VoIP is rooted in software, but it is used with lots of different kinds of hardwareeverything from next-generation IP phones to old-school rotary phones. This chapter shows you how to add these devices to your VoIP setupand how to customize them.
Chapter 6, Navigate the VoIP Network -
Voice over IP is carried over the network using packets, just like traditional data. With the advice in this chapter, you can monitor VoIP and troubleshoot it using traditional admin tools.
Chapter 7, Hard-Core Voice -
By the time you reach this chapter, you will have advanced to the hallowed ground that's held by a very exclusive crowd: the community of hard-core voice hackers. Conventions Used in This Book The following is a list of the typographical conventions used in this book:
Italics -
Used to indicate URLs, filenames, filename extensions, and directory/folder names. For example, a path in the filesystem will appear as /Developer/Applications.
Constant width -
Used to show code examples, the contents of files, console output, as well as the names of variables, commands, and other code excerpts.
Constant width bold
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Used to show user input in code and to highlight portions of code, typically new additions to old code.
Constant width italic -
Used in code examples and tables to show sample text to be replaced with your own values.
Gray type -
Used to indicate a cross-reference within the text. You should pay special attention to notes set apart from the text with the following icons:  | This is a tip, suggestion, or general note. It contains useful supplementary information about the topic at hand. |
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 | This is a warning or note of caution, often indicating that your money or your privacy might be at risk. |
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The thermometer icons, found next to each hack, indicate the relative complexity of the hack:  beginner  moderate  expert
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